1. Field of the Invention
The present invention relates to a printing apparatus for forming an image on one sheet with a first toner and a second toner by using a plurality of printing apparatuses, a printing method for the printing apparatus, and a program for executing the printing method.
2. Description of the Related Art
There is recently proposed a printing apparatus using a clear toner as a special printing material. The clear toner is a transparent printing material having the feature of adding a transparent image. Use of the clear toner enables various kinds of expressions to improve an added value of an output object. A mechanism for adding the clear toner in addition to a color toner of CMYK and the like is incorporated in the printing apparatus, thus making it possible to produce the output object using the clear toner by a single printing apparatus.
This type of apparatus, however, raises a problem that in performing a print using the special printing material such as the clear toner, a total toner amount used for the printing greatly increases as compared to a conventional print using the four-color toner.
Particularly in a case of adapting this type of apparatus to a color print of an electrophotographic process, a special printing material image is formed on an intermediate transfer member in addition to the conventional toner image of four colors of C, M, Y and K, and it is necessary to further transfer each of the formed images on a sheet.
An increase in a toner application amount as a toner amount necessary for the printing in each electrophotographic process causes an application of great loads to each process.
For example, Japanese Patent Laid-Open No. 2007-011028 discloses a method of calculating an application amount of the printable special printing material from a toner application amount of four colors of C, M, Y and K for eliminating the load of each process. However, when the application amount of the special printing material is calculated by the method disclosed by Japanese Patent Laid-Open No. 2007-011028, there are some cases where the application amount of the special printing material becomes zero. For example, in some cases a total application amount of the four-color toner exceeds a total application amount appropriately fixable and allowable on a sheet by a printer.
In such a case, even if a user instructs a print using the special printing material, since it is not possible to perform the print using the special printing material according to the user's instruction, the visual effect by the special printing material can not be obtained. For overcoming this problem, Japanese Patent Laid-Open No. 2008-139589 changes a method of forming the special printing material image when it is determined that it is not possible to perform the print using the special printing material according to the user's instruction by one time of the fixation.
According to the technology of Japanese Patent Laid-Open No. 2008-139589, first an image is printed and fixed on a sheet by using a toner other than a special printing material, and the sheet is outputted. In addition, on the sheet on which the image is printed by using the toner, the image is once more printed and fixed using the special printing material. The print by twice of the fixation is called a two-pass print. When the two-pass print is adopted, it is possible to perform a print using an amount of the special printing material more than an amount of the special printing material determined considering a total application amount allowable by the printer. Therefore, an output object having the visual effect by the special printing material desired by the user can be obtained.
It is possible to overcome the problem such as a limit of the toner amount by thus introducing the mechanism adapted for the clear toner. However, to a user not using the clear toner, the mechanism adapted specifically for the clear toner is useless in view of costs or functions.
Therefore, there is configured a system in which a printing apparatus using a color toner and a printing apparatus using a special printing material are provided as separate bodies, and a discharge unit in the printing apparatus using the color toner is connected to a feed unit in the printing apparatus using the special printing material to produce an output object using the special printing material together. In addition, for example, the system in which the printing apparatus using the color toner and the printing apparatus using the special printing material are connected is provided to a user who uses the special printing material. On the other hand, to a user not using the special printing material, only the printing apparatus using the colored tonner is provided. Thus producing the mechanism connecting the two printing apparatus allows the buildup of the system suited to a demand of a user.
However, since the structure of connecting the two printing apparatuses for use is provided with a controller for each engine, electrical power as much as that of two controllers results in being consumed all the time during the forming of the image data. According to such control, upon performing a print using only four colors CMYK of a color toner without an image data of a special color using a special printing material, control power corresponding to the two controllers is required. In this way, efficient power saving control of the controller is not conventionally performed. Further, even if a printing apparatus which has the structure of connecting the those two printing devices for use is provided, electrical power as much as that of two printing devices results in being consumed all the time. In this way, efficient power saving control of is not performed.